Computer simulations of electrokinetic transport in microfabricated channel structures

Area of Science:

• Microfluidics and Nanofluidics
• Computational Modeling
• Mass Transport Phenomena

Background:

• Microfabricated chip devices rely on electrokinetically driven mass transport.
• Understanding electrokinetic migration (electrophoresis, electroosmosis) and diffusion is crucial for device functionality.
• Accurate simulation tools are needed to design and optimize microfluidic systems.

Purpose of the Study:

• To present a mathematical model for electrokinetically driven mass transport in microfluidic chips.
• To implement the model in a computer code for simulating material transport.
• To analyze the performance of fundamental microfluidic elements like crosses and mixing tees.

Main Methods:

• Development of a 2-D mathematical model incorporating electrokinetic migration and diffusion.
• Implementation of the model into a computer code capable of handling arbitrary geometries and boundary conditions.
• Simulation of electrokinetic focusing in a cross structure and mixing in a tee structure.

Main Results:

• Identification of an optimal focusing voltage that maximizes sample concentration-to-width ratio.
• Verification of highly accurate dilution and mixing characteristics in the mixing tee for both charged and neutral samples.
• Demonstration of good agreement between simulation results and experimental data, validating the model's accuracy.

Conclusions:

• The developed mathematical model and computer code accurately simulate electrokinetic mass transport in microfluidic devices.
• The model provides valuable insights for optimizing microfluidic chip design, particularly for focusing and mixing applications.
• The simulation tool is effective for predicting the behavior of microfluidic elements with diverse sample types and geometries.